The present invention concerns a process for the manufacture of substantially spherical or spherodical particles; i.e., particles whose shape approaches that of a sphere, of metal compounds of Group II of the Periodic Table, by preciptation in a non-solvent medium of the compound in solution in a solvent.
From Japanese Patent Application 81JP164106 it is known to put a magnesium halide into solution and to precipitate it in a non-solvent organic medium. There one is dealing with a standard means of precipitation resulting in only powdered products without special shape.
Metallic compounds, particularly metal compounds of Group II of the Periodic Table, of spherical morphology are becoming increasingly sought after. These spherical compounds find their principal application as catalyst supports. In the case of, for instance, Ziegler catalysis, it is known to employ metallic salts such as MgCl.sub.2 as supports for transition metal salts active in polymerization or copolymerization of olefins. In this latter application, the morphology of the present supports is widely varied, haphazard, and uncontrolled, which is unfavorable for obtaining a high apparent density and good flowability of the polymer obtained after synthesis. It is known that these properties are clearly improved when the polymer possesses a spherical morphology resulting from a spherical morphology of the catalyst or of its support.
It is thus that according to European Patent Application 83074 a way of obtaining this morphology under the appearance of small liquid balls is described. According to this patent application, an emulsion of a compound based on magnesium and titanium is prepared in the presence of a surfactant in inert medium under very strong agitation. This technique presents the double drawback of leading to a liquid catalytic system and of excluding the possibility of fabricating a pure support likely to be used for different catalytic purposes and under different conditions.